The fate of chromium in wastewater treatment and reuse (India)

The present study explored the fate of chromium in wastewater treatment and reuse and the associated occupational health risks in Kanpur, India. The case study area is known for its leather industry and has two sewage treatment plants (STPs) and one common effluent treatment plant (CETP). The study adopted a mass balance approach to track chromium concentrations throughout the 130 MLD Jajmau STP process. It also assessed the occupational health risks of chromium exposure for STP workers and farmers who utilize STP-derived products. Data collection combined qualitative and quantitative data from key informant interviews, structured observations, and chromium analyses. The risk assessment employed a semiquantitative approach in line with WHO’s sanitation safety plan. High levels of total chromium in the influent support the hypothesis of illegal tannery discharges. Hexavalent chromium levels, considered more hazardous, remain below 100μg/L, indicating low carcinogenic risks for workers and farmers. Despite significant reductions during treatment, the STP effluent fails to meet permissible total chromium limits for irrigation. Notably, total chromium accumulates in primary sludge, posing environmental and health concerns. Implementing novel technologies could reduce effluent chromium levels, but sludge-related risks for workers remain. Swapping technologies may not substantially reduce farmers’ exposure risks, as the primary chromium source is the CETP effluent.